Java 对象拷贝复制，对象属性拷贝复制

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前言

之前写了一篇文章 java浅拷贝与深拷贝讲了如何深拷贝对象。

本文讲解如何通过第三方库来拷贝复制对象的属性值。

一、假设有Student、People类如下

public class Student {private int id;private String name;private int score;public Student() {}public Student(int id, String name, int score) {this.name = name;this.id = id;this.score = score;}//省略get、set方法
}

public class People {private int id;private String name;private int score;private int age;private String address;private String teacher;public People() {}public People(int id, String name, int score, int age, String address, String teacher) {this.id = id;this.name = name;this.score = score;this.age = age;this.address = address;this.teacher = teacher;}//省略get、set方法
}

二、方式一，使用modelmapper

1.依赖

        <dependency><groupId>org.modelmapper</groupId><artifactId>modelmapper</artifactId><version>3.2.1</version></dependency>

2.工具类

import org.modelmapper.ModelMapper;
import java.util.ArrayList;
import java.util.List;public class ConvertUtil {private static final ModelMapper MODEL_MAPPER = new ModelMapper();/*** 将源对象转换为目标类型对象。** @param source 源对象* @param targetClass 目标类型的 Class 对象* @param <S> 源对象的类型* @param <T> 目标对象的类型* @return 转换后的目标类型对象*/public static <S, T> T convert(S source, Class<T> targetClass) {return MODEL_MAPPER.map(source, targetClass);}/*** 克隆列表并将列表中的每个元素转换为目标类型。** @param sourceList 源列表* @param targetClass 目标类型的 Class 对象* @param <S> 源列表中元素的类型* @param <T> 目标列表中元素的类型* @return 转换后的目标类型列表*/public static <S, T> List<T> cloneList(List<S> sourceList, Class<T> targetClass) {List<T> targetList = new ArrayList<>();for (S source : sourceList) {T target = MODEL_MAPPER.map(source, targetClass);targetList.add(target);}return targetList;}
}

3. 测试

(1)student 与 people 的转换

		Student student = new Student(1, "张三", 98);//student转为peoplePeople people = ConvertUtil.convert(student, People.class);//输出System.out.println(people.getId());System.out.println(people.getName());System.out.println(people.getScore());System.out.println(people.getAddress());System.out.println(people.getTeacher());System.out.println("--------------------");People people1 = new People(2, "王五", 90, 28,"北京一中","王鹏");//people转为studentStudent student1 = ConvertUtil.convert(people1, Student.class);//输出System.out.println(student1.getId());System.out.println(student1.getName());System.out.println(student1.getScore());

输出的结果：

1
张三
98
null
null
--------------------
2
王五
90

(2)List<student> 与 List<people> 的转换

        Student student1 = new Student(1, "张三", 98);Student student2 = new Student(2, "李四", 95);List<Student> studentList1 = new ArrayList<>();studentList1.add(student1);studentList1.add(student2);//List<Student> 转为 List<People>List<People> peopleList1 = ConvertUtil.cloneList(studentList1, People.class);//输出peopleList1.forEach(people -> {System.out.println(people.getId());System.out.println(people.getName());System.out.println(people.getScore());System.out.println(people.getAddress());System.out.println(people.getTeacher());});System.out.println("--------------------");People people1 = new People(3, "王五", 91, 27, "北京一中", "王鹏");People people2 = new People(3, "赵二", 92, 28, "北京二中", "李梅");List<People> peopleList2 = new ArrayList<>();peopleList2.add(people1);peopleList2.add(people2);//List<People> 转为 List<Student>List<Student> studentList2 = ConvertUtil.cloneList(peopleList2, Student.class);//输出studentList2.forEach(student -> {System.out.println(student.getId());System.out.println(student.getName());System.out.println(student.getScore());});

输出的结果：

1
张三
98
null
null
2
李四
95
null
null
--------------------
3
王五
91
3
赵二
92

二、方式二，使用 Spring 的 BeanUtils

1.依赖

如果你的项目不是springboot，则需要添加如下依赖，springboot项目则不需要。

        <dependency><groupId>org.springframework</groupId><artifactId>spring-beans</artifactId><version>5.3.39</version></dependency>

2.工具类

import org.springframework.beans.BeanUtils;
import java.util.ArrayList;
import java.util.List;public class ConvertUtil {/*** 将一个对象转换为目标类型的对象** @param source      源对象* @param targetClass 目标类* @param <T>         目标类型* @return 转换后的目标对象*/public static <T> T convert(Object source, Class<T> targetClass) {if (source == null) {return null;}try {T target = targetClass.getDeclaredConstructor().newInstance();BeanUtils.copyProperties(source, target);return target;} catch (ReflectiveOperationException e) {throw new RuntimeException("转化对象失败", e);}}/*** 克隆一个列表，并将列表中的每个元素转换为目标类型的对象** @param sourceList  源列表* @param targetClass 目标类* @param <S>         源类型* @param <T>         目标类型* @return 克隆后的列表*/public static <S, T> List<T> cloneList(List<S> sourceList, Class<T> targetClass) {if (sourceList == null) {return null;}List<T> targetList = new ArrayList<>();for (S source : sourceList) {T target = convert(source, targetClass);targetList.add(target);}return targetList;}
}

3. 测试

(1)student 与 people 的转换

		Student student = new Student(1, "张三", 98);//student转为peoplePeople people = ConvertUtil.convert(student, People.class);//输出System.out.println(people.getId());System.out.println(people.getName());System.out.println(people.getScore());System.out.println(people.getAddress());System.out.println(people.getTeacher());System.out.println("--------------------");People people1 = new People(2, "王五", 90, 28,"北京一中","王鹏");//people转为studentStudent student1 = ConvertUtil.convert(people1, Student.class);//输出System.out.println(student1.getId());System.out.println(student1.getName());System.out.println(student1.getScore());

输出的结果：

1
张三
98
null
null
--------------------
2
王五
90

(2)List<student> 与 List<people> 的转换

        Student student1 = new Student(1, "张三", 98);Student student2 = new Student(2, "李四", 95);List<Student> studentList1 = new ArrayList<>();studentList1.add(student1);studentList1.add(student2);//List<Student> 转为 List<People>List<People> peopleList1 = ConvertUtil.cloneList(studentList1, People.class);//输出peopleList1.forEach(people -> {System.out.println(people.getId());System.out.println(people.getName());System.out.println(people.getScore());System.out.println(people.getAddress());System.out.println(people.getTeacher());});System.out.println("--------------------");People people1 = new People(3, "王五", 91, 27, "北京一中", "王鹏");People people2 = new People(3, "赵二", 92, 28, "北京二中", "李梅");List<People> peopleList2 = new ArrayList<>();peopleList2.add(people1);peopleList2.add(people2);//List<People> 转为 List<Student>List<Student> studentList2 = ConvertUtil.cloneList(peopleList2, Student.class);//输出studentList2.forEach(student -> {System.out.println(student.getId());System.out.println(student.getName());System.out.println(student.getScore());});

输出的结果：

1
张三
98
null
null
2
李四
95
null
null
--------------------
3
王五
91
3
赵二
92

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